The compression housing is not located on the medial line of the plate, but is peripheral to the medial line, either in the longitudinal or the medial direction of the plate.

The cross-sectional area of each channel (12) or (14), as measured in a plane perpendicular to the medial line of the channel, charges longitudinally of the channel.

The lateral centerline (C1) of the two-dimensional cross section (30) is obtained, and by using the tilt angle α of the centerline (C1), the tilt angle to the inside or the outside of the foot (10) is obtained.